Although emergency lighting systems are well known in the art, including those manufactured by the present assignee, few systems provide self-diagnostic testing of the emergency lighting system other than with the use of a manually initiated testing procedure. Such procedures typically use a test button which momentarily tests some function or functions of the system, such as lamp condition, battery charge condition, etc. It has ben found that manually tested emergency lighting systems often are not periodically tested and, therefore, a defective system may be present whose condition is unknown until an actual emergency condition arises, at which time it fails to operate. Such failure, of course, can be catastrophic and it is the intent of the present invention to provide a simple, yet effective self-diagnostic emergency lighting supervisory system for periodically testing all major components and sub-sections of fhe system to insure their proper operation and to notify responsible personnel of a faulty condition and the nature of that condition so that proper and rapid replacement or repair is achieved. The periodic testing is performed under full lamp load for set periods of time. Such full-load exercising of the battery further insures optimal battery capacity.
Although some prior art devices employ some form of self-diagnostic procedure, they do not provide the comprehensive supervisory testing capabilities of the present invention, nor the ability to communicate such information to a remote location as is disclosed and claimed herein.
More particularly, an Electronic Scanning Process emergency directional sign is manufactured by the Kurt Versen Company, 10 Charles Street, P.O. Box 677, Westwood, N.J. 07675, USA, which includes some periodic testing and self-diagnostic capabilities. According to literature distributed by the Kurt Versen Co., this system on a daily basis scans the compoonents of the system including batteries, lamps and charger to determine their operational state and, if a failure occurs in any of these elements, an external AC powered light is energized and flashes so as to inform maintenance personnel of the problem. In addition to this AC powered lamp, a green light emitting diode (LED) on the charger circuitry is lit when the charger is working and is extinguished if the charger is in need of service. The daily testing of the components of the system appears to be for a relatively brief period of time which is sufficiently long to determine whether the charger, batteries and lamps are operational.
The present invention provides for a monthly five-minute test of the various components in a self-test regime as well as a user programmable 30-, 60-, 90- or 120-minute self-test once every six months. These longer time duration testing procedures not only determine if the battery has sufficient power to illuminate the lamps for a periodd of time, but also determine whether the batteries have sufficient storage capacity to maintain illumination for periods of time which are required by relevant national and state codes. These five minute and longer discharges of the battery also provide the salutory effect of maintaining charge capacity due to the inherent characteristics of the batteries used in emergency lighting equipment which require periodic discharge in order to maintain maximum charge capacity. In addition, the present invention not only determines the state of the various system parameters, but also annunciates this information visually. It can also communicate this information to an external computer or data acquisition device which can monitor many emergency lighting systems installed throughout one or more buildings. Thus, an overall self-diagnostic testing capability is provided which is not disclosed or suggested by the prior art including the above mentioned Kurt Versen Model ESP Series Electronic Emergency Directional Signs.
Furthermore, the present invention includes other features which distinguish it from the prior art. Such features include an enhanced charging circuit with an adjustable float voltage which is temperature compensated and includes a three-step battery charger with an automatic time period for providing a battery equalization voltage. This type of battery charging enhances battery capability and reliability.
The present invention also includes full-time, on-line monitoring of both high and low battery voltage conditions and actual lamp current monitoring during self-test operation. The latter test procedure is unlike prior art systems including the above mentioned ESP system which only tests for open condition of a lamp but cannot monitor lamp failures for a loss of as little as 20-25% of the load current. The present invention can therefore determine the failure of a single lamp out of a multi-lamp system.
The present system also includes circuitry for maintaining the failure condition even if AC power is removed as well as specific annunciation of the particular problem. It further provides AC brown-out sensing and transfer to emergency power when such a condition is sensed.
Thus, the present system not only continuously senses critical system parameters, but also performs periodic self-testing of all major system components.